The present invention relates to an image forming method and apparatus and a ultrasonic imaging apparatus, and particularly to an image forming method and apparatus for forming an image of a dynamic state based on the Doppler shift of a ultrasonic echo, and to a ultrasonic imaging apparatus which is equipped with t he image forming apparatus.
Ultrasonic imaging of a dynamic state of the blood flow is based on the use of the Doppler shift of a ultrasonic echo created by small particles, such as red blood cells, included in blood. The produced image is displayed as a color Doppler image.
If it is needed to raise the magnitude, of echo for the blood portion, a ultrasonic contrast agent is put in blood. The ultrasonic contrast agent is a liquid including numerous fine bubbles having a diameter of around several xcexcm. Such contrast agent, in which fine bubbles produce an echo including the harmonics of the transmitted ultrasonic wave, is called harmonic contrast agent.
Due to the Doppler shift of a ultrasonic echo of body tissues in motion, Doppler signals which are unrelated to blood, i.e., clutters, emerge. A ultrasonic echo of body tissues further includes harmonic components due to the nonlinearity of ultrasonic transmission, and therefore clutters also emerge in the harmonic region.
Clutter""s attributable to body tissues are featured to have a large power and a small velocity as compared with blood-caused signals, and this fact is utilized to separate clutters from blood-caused signals thereby to diminish the clutters. However, this scheme is not sufficient to remove clutters completely.
It is an object of the present invention is to accomplish an image forming method and apparatus capable of producing an image of dynamic state without clutters and a ultrasonic imaging apparatus which is equipped with the image forming apparatus.
Before describing a means of solving the problem, the characteristics of a ultrasonic echo which a harmonic contrast agent produces will be explained. The harmonic contrast agent is featured to have its Doppler shift exhibiting the LOC (Loss of Correlation) phenomenon, besides the creation of a harmonic echo of the transmitted ultrasonic wave.
The velocity evaluated based on the Doppler shift having the LOC phenomenon has an extremely large variance, and it can be distinguished clearly from clutters which are generally small in variance. The present invention utilizes such characteristics of the Doppler shift of the harmonic contrast agent.
(1) The invention at a first viewpoint intending to solve the above-mentioned problem resides in an image forming method which forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of a ultrasonic echo, and is characterized by evaluating the variance of the velocity of the echo source based on the Doppler shift, and adjusting the signal strength of the image depending on the value of variance.
The invention at this viewpoint is designed to adjust the signal strength of the image depending on the value of the variance of velocity of the echo source, and in consequence it is possible to prevent clutter elements which are generally small in variance from appearing in the image. It is also possible to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance.
(2) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming method which forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of a ultrasonic echo, and is characterized by evaluating the variance of the velocity of the echo source based on the Doppler shift, and minimizing the signal strength of the image when the variance is smaller than a predetermined value.
The invention at this viewpoint is designed to minimize the signal strength of the image when the variance of the velocity of the echo source is smaller than a predetermined value, and in consequence it is possible to prevent clutter elements which are generally small in variance from appearing in the image.
(3) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming method which forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of a ultrasonic echo, and is characterized by evaluating the variance of the velocity of the echo source based on the Doppler shift, and multiplying a gain, which is given as a function of the variance, to the signal strength of the image.
The invention at this viewpoint,is designed to multiply a gain, which is given as a function of the variance, to the signal strength of the image, and in consequence it is possible to prevent clutter elements which are generally small in variance from appearing in the image. It is also possible to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance.
(4) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming method which forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of a ultrasonic echo, and is characterized by evaluating the variance of the velocity of the echo source based on the Doppler shift, evaluating the power of a signal having the Doppler shift, and multiplying a gain, which is given as a function of the variance and power, to the signal strength of the image.
The invention at this viewpoint is designed to multiply a gain, which is given as a function of the variance and power to the signal strength of the image, and in consequence it is possible to prevent clutter elements which are generally small in variance and large in power from appearing in the image. It is also possible to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance and small in power.
(5) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming method of any one of the items (1) through (4), which is characterized in that the dynamic state is the velocity.
The invention at this viewpoint is capable of producing a velocity image which is rid of clutters.
(6) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming method of any one of the items (1) through (4), which is characterized in that the dynamic state is the variance of velocity.
The invention at this viewpoint is capable of producing a variance image which is rid of clutters.
(7) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming method of any one of the items (1) through (4), which is characterized in that the dynamic state is the combination of the velocity and variance.
The invention at this viewpoint is capable of producing a velocity/variance combination image which is rid of clutters.
(8) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming method of any one of the items (1) through (4), which is characterized in that the dynamic state is the power of a signal having the Doppler shift.
The invention at this viewpoint is capable of producing a power image which is rid of clutters.
(9) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming method of any one of the items (1) through (4), which is characterized in that the dynamic state is the combination of the power of a signal having the Doppler shift and the variance of velocity.
The invention at this viewpoint is capable of producing a power/variance combination image which is rid of clutters.
(10) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming method which forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of a ultrasonic echo, and is characterized by evaluating the variance of the velocity of the echo source based on the Doppler shift, and forming the image based on a signal which is given as a function of the variance.
The invention at this viewpoint is designed to form an image based on a signal which is given as a function of the variance, and in consequence it is possible to prevent clutter elements which are generally small in variance from appearing in the image. It is also possible to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance.
(11) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming method which forms an image, indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of a ultrasonic echo, and is characterized by evaluating the variance of the velocity of the echo source based on the Doppler shift, evaluating the power of a signal having the Doppler shift, and forming the image based on a signal which is given as a function of the variance and power.
The invention at this viewpoint is designed to form an image based on a signal which is given as a function of the variance and power, and in consequence it is possible to prevent clutter elements which are generally small in variance and large in power from appearing in the image. It is also possible to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance and small in power.
(12) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming apparatus which forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of a ultrasonic echo, and is characterized by comprising a variance calculation means which evaluates the variance of the velocity of the echo source based on the Doppler shift, and a signal strength adjusting means which adjusts the signal strength of the image depending on the value of variance.
The invention at this viewpoint is designed so that the signal strength adjusting means adjusts the signal strength of the image depending on the value of the variance of velocity of the echo source, and in consequence it is possible to prevent clutter elements which are generally small in variance from appearing in the image. It is also possible to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance.
(13) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming apparatus which forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of a ultrasonic echo, and is characterized by comprising a variance calculation means which evaluates the variance of the velocity of the echo source based on the Doppler shift, and a signal strength adjusting means which minimizes the signal strength of the image when the variance is smaller than a predetermined value.
The present invention at this viewpoint is designed so that the signal strength adjusting means minimizes the signal strength of the image when the variance of the velocity of the echo source is smaller than a predetermined value, and in consequence it is possible to prevent clutter elements which are generally small in variance from appearing in the image.
(14) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming apparatus which forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of a ultrasonic echo, and is characterized by comprising a variance calculation means which evaluates the variance of the velocity of the echo source based on the Doppler shift, and a signal strength adjusting means which multiplies a gain, which is given as a function of the variance, to the signal strength of the image.
The invention at this viewpoint is designed so that the signal strength adjusting means multiplies a gain, which is given as a function of the variance, to the signal strength of the image, and in consequence it is possible to prevent clutter elements which are generally small in variance from appearing in the image. It is also possible to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance.
(15) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming apparatus which forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of a ultrasonic echo, and is characterized by comprising a variance calculation means which evaluates the variance of the velocity of the echo source based on the Doppler shift, a power calculation means which evaluates the power of a signal having the Doppler shift, and a signal strength adjusting means which multiplies a gain, which is given as a function of the variance and power, to the signal strength of the image.
The invention at this viewpoint is designed so that the signal strength adjusting means multiplies a gain, which is given as a function of the variance and power, to the signal strength of the image, and in consequence it is possible to prevent clutter elements which are generally small in variance and large in power from appearing in the image. It is also possible to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance and small in power.
(16) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming apparatus of any one of the items (12) through (15), which is characterized in that the dynamic state is the velocity.
The invention at this viewpoint is capable of producing a velocity image which is rid of clutters.
(17) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming apparatus of any one of the items (12) through (15), which is characterized in that the dynamic state is the variance of velocity.
The invention at this viewpoint is capable of producing a velocity image which is rid of clutters.
(18) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming apparatus of any one of the items (12) through (15), which is characterized in that the dynamic state is the combination of the velocity and variance.
The invention at this viewpoint is capable of producing a velocity/variance combination image which is rid of clutters.
(19) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming apparatus of any one of the items (12) through (15), which is characterized in that the dynamic state is the power of a signal having the Doppler shift.
The invention at this viewpoint is capable of producing a power image which is rid of clutters.
(20) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming apparatus of any one of the items (13) through (16), which is characterized in that the dynamic state is the combination of the power of a signal having the Doppler shift and the variance of velocity.
The invention at this viewpoint is capable of producing a power/variance combination image which is rid of clutters.
(21) The invention at other viewpoint intending to solve the above-mentioned problem.resides in an image forming apparatus which forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of a ultrasonic echo, and is characterized by comprising a variance calculation means which evaluates the variance of the velocity of the echo source based on the Doppler shift, and an image forming means which forms the image based on a signal which is given as a function of the variance.
The invention at this viewpoint is designed so that the image forming means forms an image based on a signal which is given as a function of the variance, and in consequence it is possible to prevent clutter elements which are generally small in variance from appearing in the image. It is also possible to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance.
(22) The invention at other viewpoint intending to solve the above-mentioned problem resides in an image forming apparatus which forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of a ultrasonic echo, and is characterized by comprising a variance calculation means which evaluates the variance of the velocity of the echo source based on the Doppler shift, a power calculation means which evaluates the power of a signal having the Doppler shift, and an image forming means which forms the image based on a signal which is given as a function of the variance and power.
The invention at this viewpoint is designed so that the image forming means forms an image based on a signal which is given as a function of the variance and power, and in consequence it is possible to prevent clutter elements which are generally small in variance and large in power from appearing in the image. It is also possible, to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance and small in power.
(23) The invention at other viewpoint intending to solve the above-mentioned problem resides in a ultrasonic imaging apparatus which transmits a ultrasonic wave, receives an echo thereof, and forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of the ultrasonic echo, and is characterized by comprising a variance calculation means which evaluates the variance of the velocity of the echo source based on the Doppler shift, and a signal strength adjusting means which adjusts the signal strength of the image depending on the value of variance.
The inventions at this viewpoint is designed so that the signal strength adjusting means adjusts the signal strength of the image depending on the value of the variance of velocity of the echo source, and in consequence it is possible to prevent clutter elements which are generally small in variance from appearing in the image. It is also possible to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance.
(24) The invention at other viewpoint intending to solve the above-mentioned problem resides in a ultrasonic imaging apparatus which transmits a ultrasonic wave, receives an echo thereof, and forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of the ultrasonic echo, and is characterized by comprising a variance calculation means which evaluates the variance of the velocity of the echo source based on the Doppler shift, and a signal strength adjusting means which minimizes the signal strength of the image when the variance is smaller than a predetermined value.
The invention at this viewpoint is designed so that the signal strength adjusting means minimizes the signal strength of the image when the variance is smaller than a predetermined value, and in consequence it is possible to prevent clutter elements which are generally small in variance from appearing in the image.
(25) The invention at other viewpoint intending to solve the above-mentioned problem resides in a ultrasonic imaging apparatus which transmits a ultrasonic wave, receives an echo thereof, and forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of the ultrasonic echo, and is characterized by comprising a variance calculation means which evaluates the variance of the velocity of the echo source based on the Doppler shift, and a signal, strength adjusting means which multiplies a gain, which is given as a function of the variance, to the signal strength of the image.
The invention at this viewpoint is designed so that the signal strength adjusting means multiplies a gain, which is given as a function of the variance, to the signal strength of the image, and in consequence it is possible to prevent clutter elements which are generally small in variance from appearing in the image it is also possible to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance.
(26) The invention at other viewpoint intending to solve the above-mentioned problem resides in a ultrasonic imaging apparatus which transmits a ultrasonic wave, receives an echo thereof, and forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of the ultrasonic echo, and is characterized by comprising a variance calculation means which evaluates the variance of the velocity of the echo source based on the Doppler shift, a power calculation means which evaluates the power of a signal having the Doppler shift, and a signal strength adjusting means which multiplies a gain, which is given as a function of the variance and power, to the signal strength of the image.
The invention at this viewpoint is designed so that the signal strength adjusting means multiplies a gain, which is given as a function of the variance and power, to the signal strength of the image, and in consequence it is possible to prevent clutter elements which are generally small in variance and large in power from appearing in the image. It is also possible to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance and small in power.
(27) The invention at other viewpoint intending to solve the above-mentioned problem resides in a ultrasonic imaging apparatus of any one of the items (23) through (26), which is characterized in that the dynamic state is the velocity.
The invention,at this viewpoint is capable of producing a velocity image which is rid of clutters.
(28) The invention at other viewpoint intending to solve the above-mentioned problem resides in a ultrasonic imaging apparatus of any one of the items (23) through (26), which is characterized in that the dynamic state is the variance of velocity.
The invention at this viewpoint is capable of producing a variance image which is rid of clutters.
(29) The invention at other viewpoint intending to solve the above-mentioned problem resides in a ultrasonic imaging apparatus of any one of the items (23) through (26), which is characterized in that the dynamic state is the combination of the velocity and variance.
The invention at this viewpoint is capable of producing a velocity/variance combination image which is rid of clutters.
(30) The invention at other viewpoint intending to solve the above-mentioned problem resides in a ultrasonic imaging apparatus of any one of the items (23) through (26), which is characterized in that the dynamic state is the power of a signal having the Doppler shift.
The invention at this viewpoint is capable of producing a power image which is rid of clutters.
(31) The invention at other viewpoint intending to solve the above-mentioned problem resides in a ultrasonic imaging apparatus of any one of the items (23) through (26) which is characterized in that the dynamic state is the combination of the power of a signal having the Doppler shift and the variance of velocity.
The invention at this viewpoint is capable of producing a power/variance combination image which is rid of clutters.
(32) The invention at other viewpoint intending to solve the above-mentioned problem resides in a ultrasonic imaging apparatus which transmits a ultrasonic wave, receives an echo thereof, and forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of the ultrasonic echo, and is characterized by comprising a variance calculation means which evaluates the variance of the velocity of the echo source based on the Doppler shift, and an image, forming means which forms the image based on a signal which is given as a function of the variance.
The invention, at this viewpoint is designed so that the image forming means forms an image based on a signal which is given as a function of the variance, and in consequence it is possible to prevent clutter elements which are generally small in variance from appearing in the image. It is also possible to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance.
(33) The invention at other viewpoint intending to solve the above-mentioned problem resides in a ultrasonic imaging apparatus which transmits a ultrasonic wave, receives an echo thereof, and forms an image indicative of a dynamic state of an echo source containing a harmonic contrast agent based on the Doppler shift of the ultrasonic echo, and is characterized by comprising a variance calculation means which evaluates the variance of the velocity of the echo source based on the Doppler shift, a power calculation means which evaluates the power of a signal having the Doppler shift, and an image forming means which forms the image based on a signal which is given as a function of the variance and power.
The invention at this viewpoint is designed so that the image forming means forms an image based on a signal which is given as a function of the variance and power, and in consequence it is possible to prevent clutter elements which are generally small in variance and large in power from appearing in the image. It is also possible to emphasize the dynamic state image of the harmonic contrast agent which is generally large in variance and small in power.
Therefore, the present invention can accomplish an image forming method and apparatus capable of producing a dynamic state image without clutters and a ultrasonic imaging apparatus which is equipped with the image forming apparatus.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying invention.